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FirstNonZero, FirstNonZeroPos

Syntax

FirstNonZero(V:VECTOR):POLY
FirstNonZeroPos(V:VECTOR):POLY
    

Summary

the first non-zero entry in a vector

Description

The first function returns the first non-zero entry of V. The second function returns the index of the first non-zero entry of V. If either function is handed a zero vector then an error is signalled.

example

    
Use R ::= Q[x,y,z];
V := Vector(0,0,x^2+yz,0,z^2);
FirstNonZero(V);
x^2 + yz
-------------------------------
FirstNonZeroPos(V);
3
-------------------------------
V[FirstNonZeroPos(V)];
x^2 + yz
-------------------------------
        
    

See Also